Linux/TDA2: question about vmem-exp

John G

Prodigy 235 points

Part Number: TDA2

Tool/software: Linux

hi , TI experts,

I am using Linux usecase (OV490 3D srv ) in vision SDK 3.04.00.

Now my problem is that the display output only tex[0], tex[3], tex[1] and tex[2] are same with tex[1], tex[3].

I find out in vmem-exp.c ( kernel driver ), vmem_export_single function export the 2 video virtual addr （such as 0xa7a2b000, 0xa7a2b500）

to a same dmafd. It seems like the PAGE_MASK (4K Align) mask the offset(0x500).

If this, how GPU map the correct physical address ? I mean, the same dmafd get 2 different address (such as YUV 0xa7a2b000, 0xa7a2b500) ?

regards,

John

over 6 years ago

0 Nikhil Devshatwar over 6 years ago

TI__Genius 9905 points

Hello,

This is a standard Linux limitation in Linux.

DMABUF can be used only to export certain pages from the kernel

For GPU, most likely, one of the following should work

- just pass one dmabuf, GPU finds out the UV offset based on the size of Y

- pass the same dmabuf for both Y and UV and provide offset values

Regards,

Nikhil D

0 John G over 6 years ago in reply to Nikhil Devshatwar

Prodigy 235 points

Hi ,Nikhil
thanks for reply.
"- pass the same dmabuf for both Y and UV and provide offset values"
In Vision SDK SGX drivers, I cannot find the provided offset values in System_eglWindowGetTexYuv().
For frameBuffer as below:
Y1 Y2
UV1 UV2
It can only checkout the Y1 and UV1, Y2 and UV2 are missed.
Can u give me more tips to find offset manipulation?
regards,
John

0 Subhajit Paul over 6 years ago in reply to John G

TI__Expert 7015 points

John, are you still facing this issue? I am closing this thread.

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Linux/TDA2: question about vmem-exp